Question

In my application i parse a xml from which I get a list of items (hotels and restaurants) that i put into array “listElements”; I need to get from this array, another array that will contain only the particular elements (hotels only) and then I need to get from this array, three array that will contain hotels according to stars(array5starhotel, array4starhotel,array3starhotel). How can do this?
This is the code I used for parsing(I used TBXML):

- (void)loadCategories {
    // instantiate an array to hold categories objects
    listCategories = [[NSMutableArray alloc] initWithCapacity:100];

    tbxml = [[TBXML tbxmlWithXMLFile:@"Molise.xml"] retain];

    // Obtain root element
    TBXMLElement * root = tbxml.rootXMLElement;

    // if an author element was found
    if (root) {
      //search for the first category element within the root element's children
      TBXMLElement * category = [TBXML childElementNamed:@"category" parentElement:root];

      // if a category element was found
      while (category != nil) {

        // instantiate a category object
        Category * aCategory = [[Category alloc] init];

        // get the name attribute from the category element
        aCategory.name = [TBXML valueOfAttributeNamed:@"name" forElement:category];

        // search the category's child elements for a "element" element
        TBXMLElement * element = [TBXML childElementNamed:@"element" parentElement:category];

        // if a "element" element was found     
        while (element != nil) {                              

          // instantiate a "element" object
          Element * aElement = [[Element alloc] init];

          // extract the attributes from the "element" element
          aElement.title = [TBXML valueOfAttributeNamed:@"title" forElement:element];
          aElement.address = [TBXML valueOfAttributeNamed:@"address" forElement:element];          
          aElement.stars =[TBXML valueOfAttributeNamed:@"stars" forElement:element];

          // add the "element" object to the category's listElements array and release the resource       
          [aCategory.listElements addObject:aElement];
          [aElement release];

          // find the next sibling element named "element"
          element = [TBXML nextSiblingNamed:@"element" searchFromElement:element];
        }

        // add our category object to the listCategories array and release the resource  
        [listaCategories addObject:aCategory];
        [aCategory release];

        // find the next sibling element named "category"
        category = [TBXML nextSiblingNamed:@"category" searchFromElement:category];
      }                      

      [tbxml release];
    }

Answer 1

OK, so your code snippet doesn’t do what the question says it does.

You make an array of categories (listCategories) containing lots of Category objects. Each of these contains a listElements array.

Assuming that you want the items from the ‘hotels’ category . . .

// Get the hotels category
Category *hotelsCategory = nil;
for (Category *temp in listCategories.each) {
  if ([temp.name isEqualToString:@"hotel"]) {
    hotelsCategory = temp;
    break;
  }
}
if (nil == hotelsCategory)
  return NSLog(@"No hotels category found");

// Get the hotels from this category with a 3 or above star rating
NSMutableArray *array5starhotel = [NSMutableArray array];
NSMutableArray *array4starhotel = [NSMutableArray array];
NSMutableArray *array3starhotel = [NSMutableArray array];
for (Element *element in hotelsCategory.listElements) {
  if ([element.stars isEqualToString:@"5"])
    [array5starhotel addObject:element];
  if ([element.stars isEqualToString:@"4"])
    [array4starhotel addObject:element];
  if ([element.stars isEqualToString:@"3"])
    [array3starhotel addObject:element];
}

Hope that helps – I’ve had to guess at some stuff because I don’t know what’s in a Category or Element object!